Well it was Firefox the last time you mentioned it!
If you've got 'File / Edit/ View / . . .' etc across the top of your screen, go to Help and then About xxxx (where xxxx is the name of your browser). When I do that I see Firefox 35.0.1
If you've not got 'File / Edit/ View / . . .' etc across the top of your screen, right-click at the top of your screen and put a tick against 'Menu bar'. You can then follow my instructions above.
Which icon do you click when you went to get on the internet- is it big blue lower case e in which case it's a version of IE, is it a large lower case g (Google) or a red, green and yellow circle that's blue in the middle (Chrome)